If I ever told you I like apples: I lied.
If I ever told you I like apples; I lied.
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This needs to be a comma because the first part of the sentence ("If I ever told you I like apples") cannot stand on its own as a sentence; "I lied" is needed for it to make sense. This is called a 'dependent clause'.
If the two clauses were independent (they could stand on their own as sentences), then a semicolon would be needed. To use a comma between two independent clauses is known as 'comma splicing' and is considered grammatically incorrect.
Hope the background info helps.